Alloy Steel Grade 11 Explained
Alloy Steel Grade 11 is a 1.25% chromium–0.5% molybdenum alloy steel designed for improved strength and oxidation resistance in elevated temperature environments. It is commonly used in pressure vessels, turbines, superheaters, and structural components in thermal power plants and refineries. Grade 11 exhibits excellent creep resistance and good mechanical stability under cyclic thermal loading. With proper heat treatment, it offers good weldability and long service life, making Alloy Steel Grade 11 sheets and plates ideal for demanding high-temperature and pressure applications.
GR 11 ALLOY STEEL SHEETS AND PLATES EQUIVALENT GRADES
| STANDARD | UNS |
|---|---|
| A387 / SA387 | K11789 |
SPECIFICATION OF ALLOY STEEL GR 11 SHEETS AND PLATES
| Standard | ASTM A387 / ASME SA387 |
|---|---|
| Dimension Standard | JIS, AISI, ASTM, GB, DIN, EN, etc |
| Width | 1000mm, 1219mm, 1500mm, 1800mm, 2000mm, 2500mm, 3000mm, 3500mm, etc |
| Length | 2000mm, 2440mm, 3000mm, 5800mm, 6000mm, etc |
| Thickness | 0.3 mm to 120 mm |
| Form | Coils, Foils, Rolls, Plain Sheet, Shim Sheet, Perforated Sheet, Chequered Plate, Strip, Flats, Blank (Circle), Ring (Flange) etc. |
| Surface Finishing | Hot rolled plate (HR), Cold rolled sheet (CR), 2B, 2D, BA, NO.1, NO.4, NO.8, 8K, mirror, Chequered, embossed, hair line, sand blast, Brush, etching, SATIN (Met with Plastic Coated) etc. |
CHEMICAL COMPOSITION OF ALLOY STEEL GR 11 SHEETS AND PLATES
| C% | Mn% | P% | S% | Si% | Cr% | Mo% |
|---|---|---|---|---|---|---|
| 0.04-0.17 | 0.35-0.73 | 0.035 max | 0.035 max | 0.44-0.86 | 0.94-1.56 | 0.40-0.7 |
MECHANICAL PROPERTIES OF ALLOY STEEL GR 11 SHEETS AND PLATES
| Property | Class 1 | Class 2 |
|---|---|---|
| Tensile Strength (ksi) | 60-85 | 75-90 |
| Tensile Strength (MPa) | 415-585 | 485-620 |
| Yield Strength (ksi) | 35 | 45 |
| Yield Strength (MPa) | 240 | 310 |
| Elongation in 200mm (%) | 19 | 18 |
| Elongation in 50mm (%) | 22 | 22 |
💡 Practical Difference in Use
Use Alloy Steel Grade 11 when: high-temperature strength, creep resistance, and toughness are required in long-term service, especially in power plant components and pressure vessels. → Example: high-pressure boilers, steam turbines, heat exchangers, and piping systems in power generation and petrochemical industries.
Applications of Alloy Steel Grade 11 Sheets and Plates
Alloy Steel Grade 11 is a chromium-molybdenum steel designed for high-temperature applications, providing excellent strength, creep resistance, and reliability over extended periods.
- Power Generation: Steam turbines, boilers, superheaters, and heat exchangers.
- Pressure Vessels: High-pressure reactors and storage vessels.
- Piping Systems: High-temperature pipelines in power plants and refineries.
When to Choose Alloy Steel Grade 11?
Alloy Steel Grade 11 is selected for applications requiring long-term reliability under high temperatures and pressures, where creep and fatigue resistance are essential.
Choose Alloy Steel Grade 11 when:
- Operating temperatures reach 550–600°C
- High creep and fatigue resistance is required
- Used in high-pressure boilers, turbines, and piping systems
- Durability and weldability are critical for long-term service
- Reliability under high-temperature steam or chemical exposure is important
Industries That Use Alloy Steel Grade 11 Sheets and Plates
Alloy Steel Grade 11 is commonly used in industries where high-temperature and high-pressure service is critical for safety and performance.
Primary application in boilers, turbines, and high-temperature piping.
Uses
Superheaters, steam lines, and heat exchangers.
Why Alloy Steel Grade 11?
Superior creep strength and reliability at elevated temperatures.
Used in high-pressure equipment and high-temperature pipelines.
Uses
Refinery piping, reactor vessels, and high-temperature valves.
Why Alloy Steel Grade 11?
Excellent resistance to thermal fatigue and creep rupture.
Used where long-term high-temperature resistance is required.
Uses
Pressure vessels, piping systems, and high-temperature reactors.
Why Alloy Steel Grade 11?
High strength and durability under severe chemical and thermal conditions.
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